Contributions of long‐distance dust transport to atmospheric P inputs in the Yucatan Peninsula

Atmospheric deposition is not typically considered in conceptual models of P cycling in terrestrial ecosystems, but in P‐limited tropical forests that receive significant inputs of dust, it may play an important role in sustaining ecosystem productivity. We used models and observations to quantify total atmospheric P inputs and the contribution of long‐distance dust transport to tropical dry forests in the Yucatan peninsula over a 10 year period. Total atmospheric P input was estimated from atmospheric bulk deposition sampling in the southern Yucatan peninsula in 2007 and 2010–2011, and P input from dust deposition was estimated using two independent methods: zonal dust flux divergence based on MODIS AOD retrievals, and MATCH atmospheric transport modeling. Total atmospheric P input was 265 ± 80 g P ha ‐1 yr ‐1 , and dust P input was 46 ± 12 g P ha ‐1 yr ‐1 . There was significant seasonal and interannual variation, with local biomass burning accounting for high P inputs in April and May, and dust transport from June through August. We found that MATCH underestimates P deposition from dust to the Yucatan because of underestimation of dust transport relative to MODIS remote sensing. Dust accounted for 25% of total atmospheric P inputs in the Yucatan, indicating local sources dominate atmospheric inputs. However, dust is still an important source of P for tropical dry forests in the Yucatan since it is a new input of P that occurs during the early growing season of the forest, and is large enough to offset leaching and erosional losses from soils.